Related Experiment Video
Updated: Aug 1, 2026
Physiology Lab Demonstration: Glomerular Filtration Rate in a Rat
Published on: July 26, 2015
Renal function in sick very low birthweight infants: 1. Glomerular filtration rate
1Department of Child Health, Bristol University.
Insights
Glomerular filtration rate (GFR) in premature infants increases with postconceptional age, independent of illness or nitrogen intake. This indicates a preprogrammed developmental trajectory for kidney function in neonates.
Area of Science:
- Neonatology
- Pediatric Nephrology
- Physiology
Background:
- Assessing kidney function in premature infants is crucial for clinical management.
- Glomerular filtration rate (GFR) is a key indicator of renal function.
- Polyfructoside clearance offers a reliable method for GFR measurement in neonates.
Purpose of the Study:
- To measure and analyze polyfructoside clearance as a marker of GFR in preterm infants.
- To determine the relationship between GFR and postconceptional age in this population.
- To investigate factors influencing GFR, including infant health status and nutritional intake.
Main Methods:
- 135 polyfructoside clearance measurements were performed in 39 infants (25.5-33 weeks' gestation).
- Infants ranged in age from 0.5 to 33 days.
- GFR was correlated with postconceptional age and body weight.
Main Results:
- GFR demonstrated an exponential increase with postconceptional age, from 0.59 ml/min at 26 weeks to 1.40 ml/min at 33 weeks.
- GFR was consistent between the first week of life and later ages for a given postconceptional age.
- Infant illness severity and nitrogen intake did not significantly affect GFR.
Conclusions:
- Neonatal GFR follows a preprogrammed postnatal increase, largely independent of external factors like illness or nutrition.
- Weight changes in preterm infants can lead to inaccurate GFR per kilogram calculations.
- This study provides normative data for GFR development in preterm neonates.
Abstract:
A total of 135 measurements of polyfructoside clearance as a measure of glomerular filtration rate (GFR) were made in 39 infants of 25.5-33 weeks' gestation, birth weight 720-2000 g, between the ages of 0.5 and 33 days. GRF was related to postconceptional age and increased exponentially from geometric mean 0.59 ml/min at 26 weeks' postconceptional age to 1.40 ml/min at 33 weeks. GFR in the first week and GFR at later ages were the same for a given postconceptional age. GFR was the same in sick infants with severe ventilatory failure as in less ill infants. There was no evidence that GFR was influenced by nitrogen input. GFR increases postnatally in a preprogrammed way irrespective of other postnatal events. When factored by body weight GFR in the first week increased only little from arithmetic mean 0.70 ml/min/kg at 26 weeks to 0.84 ml/min/kg at 33 weeks, but older infants often had a falsely high GFR per kg when they lost weight in the first week or two after birth or failed to gain weight later.
Related Concept Videos
01:28Glomerular Filtration Rate and its Regulation
GFR regulation involves two primary intrinsic controls: the myogenic and tubuloglomerular feedback mechanisms.
The myogenic...
01:23Renal Clearance
Renal clearance refers to the volume of plasma cleared of a specific substance, such as creatinine, per unit of time. To measure clearance, urine samples are collected over a 24-hour period during each bladder voiding, followed by a single blood sample at the...
01:17Factors Affecting Renal Clearance: Renal Impairment
One condition associated with renal failure is uremia. Uremia is characterized by impaired glomerular filtration and fluid accumulation in the body. This condition hinders the renal clearance of drugs, resulting in drug accumulation and potential...
01:25Drug Dosing in Renal Diseases: Measurement of Glomerular Filtration Rate
01:28Drug Dosing in Renal Diseases: Estimation of Glomerular Filtration Rate Based on Serum Creatinine Concentration
01:29Physiology of the Genitourinary System I: Renal Blood Flow and Glomerular Filtration